Starting and idling of an automotive vehicle's internal combustion engine during cold weather may subject various engine parts to harsher operating conditions than those experienced during warmer weather and/or after the engine has warmed up. An engine's valve train, for example, may contain such parts. Combustion processes occurring during cold weather starting and idling may be incomplete, and over time cause certain products of such incomplete combustion to accumulate as deposits that can affect proper valve train operation.
The present invention relates to an improvement for reducing, and ideally eliminating, accumulation of products of incomplete combustion that result from cold ambient conditions acting on the engine and that otherwise might ultimately affect engine operation before the useful life of an engine has elapsed.
A presently preferred embodiment of the invention is well-suited for integration with an engine electronic control. One example of a engine electronic control with which the present invention is useful may be found in U.S. Pat. No. 5,357,912 relating to a diesel engine.
One general aspect of the invention relates to an idle speed control for an internal combustion engine comprising a first source providing a signal corresponding to ambient air temperature, a second source providing a signal corresponding to engine coolant temperature, a third source providing a signal indicating that an engine is running substantially in an idle condition, and a processor that processes the signals from the first source, the second source, and the third source to develop an idle speed control signal for controlling engine idle speed by regulating the engine coolant temperature to a defined coolant temperature when the engine is running in an idle condition and the ambient air temperature does not concurrently exceed a defined air temperature.
Another general aspect of the invention relates to an idle speed control for an internal combustion engine that powers an automotive vehicle via a vehicle drivetrain comprising multiple sources providing respective signals relating to respective parameters of automotive vehicle operation, one of which signals is an ambient air temperature signal, and a processor that processes the respective signals to develop an idle speed control signal that controls engine idle speed when the engine is running in an idle condition and the ambient air temperature does not concurrently exceed a defined temperature.
Still another general aspect of the invention relates to an automotive vehicle having an engine that powers the vehicle via a drivetrain, and an electronic engine control for controlling functions related to operation of the engine, and comprising multiple sources providing respective signals relating to respective parameters relevant to vehicle operation, one of which signals is an ambient air temperature signal, and a processor that processes the respective signals to develop a speed control signal for controlling engine speed when the engine is running disengaged from the drivetrain and when the ambient air temperature does not concurrently exceed a defined temperature.
Still another general aspect of the invention relates to an automotive vehicle having an engine that powers the vehicle via a drivetrain, and an electronic engine control for controlling functions related to operation of the engine, and comprising multiple sources providing respective signals relating to respective parameters relevant to vehicle operation, a first of which signals is an ambient air temperature signal representing current ambient air temperature and a second of which is an engine coolant temperature signal representing current engine coolant temperature, and a processor that processes the respective signals to develop a speed control signal for controlling engine speed by regulating the engine coolant temperature to a defined coolant temperature when the engine is running disengaged from the drivetrain and the ambient air temperature does not concurrently exceed a defined air temperature.
Other aspects of the invention concern regulating the engine coolant temperature to substantially 63.degree. C. (145.4.degree.F.) when the engine is running in an idle condition and the ambient air temperature does not concurrently exceed substantially 0.degree.C. (32.degree. F.), the incorporation of a proportional and integral control that processes an error signal developed from engine coolant temperature feedback to the processor to develop the idle speed control signal, and the incorporation of a fault detection circuit.